The front part of a vehicle plays an essential role in case of impact, in particular during a frontal impact. In particular, the front part of a vehicle must be capable of participating in shock absorption, i.e., in contributing to the absorption and dissipation of the forces created by the impact.
The behavior of the front part of the vehicle during impacts is subject to constraints, some of which are described in a standardized way. These in particular involve standards governing the behavior of the front part during a low-speed impact, also called repairability impact, and during a high-speed impact.
In order to improve the behavior of the front part, in particular in case of high-speed impact, it is advantageous to configure this front part so as to distribute the forces created during an impact on several load paths, in particular to distribute these forces between the upper area, the middle area and the low area of the front part of the vehicle.
The middle area generally comprises two stringers extending in a longitudinal direction of the vehicle, the two stringers of the middle area further being connected by a transverse beam.
The low area generally includes a cradle, or front cradle, intended to support the front suspension of the vehicle. The low area also includes two extensions positioned on each side of the vehicle, each extension including a first elongate part extending from the front cradle toward the rear of the vehicle, in a substantially longitudinal direction. Such a low area structure is in particular described in document FR 2,887,211 A1.
The extension is connected directly or indirectly to the front cradle, and is configured to absorb forces generated by an impact, in particular frontal, and to cause at least some of these forces to pass toward the front cradle.
During a high-speed frontal impact, the vehicle experiences an impact against an obstacle at a speed exceeding 50 km/h.
During a low-speed frontal impact, the vehicle experiences an impact against an obstacle at a speed of about 16 km/h. When such impacts occur, the chassis of the vehicle, in particular its stringers, the front cradle and the extensions of the low area, must not be plastically deformed.
The requirements in terms of weight and behavior during high-speed frontal impact have recently led to causing increasingly significant forces to pass through the front low area of the vehicle.
However, the absorption of increasingly significant forces by the front low area during high-speed frontal impacts has led to subjecting the front low area to increased forces during low-speed frontal impacts, and thus altering the behavior of the low area during such low-speed impacts, in particular plastically deforming the cradle under the effect of the forces transmitted by the extensions.